1、 RPV and Primary Circuit Inspection Pressure Vessel Inspection Codes for phased Arrays M.Moles,Olympus NDT,Canada ABSTRACT Pressure vessel and piping welds require inspection to code worldwide to minimize failures due to the presence of weld defects,and this applies in particular to nuclear reactors
2、.Ultrasonic phased arrays are now commercial cost-effective.In particular,they offer major benefits over traditional radiography for weld inspections.Specifically,phased arrays are rapid,flexible and auditable when encoded scanning is used.In addition,phased arrays have no safety problems,no environ
3、mental effects and minimal data storage requirements.However,all new technologies must follow a set or rules,or codes,to guarantee reasonable and reliable defect detection,and that a suitable process is followed.Arguably,the world leader in pressure vessel codes is ASME,and Section V of ASME for new
4、 construction welds has been very active in developing Codes and Code Cases specifically for phased array inspection of pressure vessel and piping welds.This paper describes the evolution of new inspection codes for phased arrays,specifically the issues that arose with introducing phased array codes
5、,such as:manual vs.encoded scanning,calibration of all beams(particularly for S-scans),scanning patterns(linear or raster),bevel angle incidence and coverage.In addition,a brief status update is given on other North American ultrasonic inspection codes,such as API,AWS and ASTM.INTRODUCTION Ultrasoni
6、c phased arrays are now commercially cost-effective,and used extensively for both in-service and construction applications.In particular,they offer major benefits over traditional radiography for weld inspections.Specifically,phased arrays are rapid,flexible and auditable when encoded scanning is us
7、ed.In addition,phased arrays have no safety problems,no environmental side-effects and minimal data storage requirements.However,all NDT technologies must follow a set or rules,or codes,to guarantee reasonable and reliable defect detection,and that a suitable process is followed.Pressure vessel and
8、piping welds require inspection to code worldwide to minimize failures due to the presence of weld defects,and this applies in particular to phased arrays.Arguably,the world leader in pressure vessel codes is ASME,and Section V of ASME for new construction welds has been very active in developing Co
9、des and Code Cases specifically for phased array inspection of pressure vessel and piping welds.This paper describes the evolution of new inspection codes for phased arrays,specifically the issues that arose with introducing phased array codes,such as:manual vs.encoded scanning,calibration of all be
10、ams(particularly for S-scans),scanning patterns(linear or raster),bevel angle incidence and coverage.In addition,a brief status update is given on other North American ultrasonic inspection codes,such as API,AWS and ASTM.PHASED ARRAYS Industrial phased arrays are a new technology,but are based on th
11、e same principles as other wave physics,plus“phasing”.However,phased arrays are behind the development of related technologies like radar,sonar,medical ultrasonics and geophysics since the market is much smaller,and there are also specific issues:smaller wavelengths,different wave modes,wide variety
12、 of components and materials.Phased arrays have been well-described elsewhere(1),so only a brief description will be included here.Essentially,an array of separate elements is individually pulsed,with applied time delays.The software permits the operator to define the angles,focal distances,scan pat
13、terns,and other parameters;the software then calculates all the time delays to permit“phasing”and constructive and destructive interference for steering the beam through a range of angles,scanning the beam along axes,focusing the beam and using multiple scan patterns.Figure 1 shows illustrations of
14、electronic scanning(E-scans)and sweeping the beam(S-scans).Figure 1-Top,E-scan to perform corrosion.Bottom,S-scan on turbine blade root.CODES-American Society of Mechanical Engineers(ASME)ASME has been the leader in pressure vessel construction regulation for over a century,and is arguably still the
15、 leader.ASME has developed a full multi-section Code for pressure vessels,which includes Section V on NDE.Within Section V,Article 4 covers ultrasonic testing,and new techniques and technologies are introduced as Code Cases(initially),followed by Mandatory or NonMandatory Appendices(2).Section V has
16、 been successful recently in introducing new regulations for both Time-Of-Flight Diffraction(3)and phased arrays(4),arguably the two most significant developments in weld inspection in the last decades.The normal procedure for ASME to develop a new or modified code is through the appropriate Working Group(Ultrasonics in this case),which argues the regulations on technical and literary grounds.This draft code case is then passed up to the Main Committee,balloted,negatives accommodated,and finally
